# HAProxy returns 404 sometimes even though the backend server is running

**URL:** <https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628>\
**Category:** Help!\
**Created:** [February 22, 2025, 11:55am UTC](https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628 "2025-02-22T11:55:56Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Tom2](https://avatars.discourse-cdn.com/v4/letter/t/97f17d/32.png) [@Tom2](https://discourse.haproxy.org/u/Tom2)\
**Post date:** [February 22, 2025, 11:55am UTC](https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628/1 "2025-02-22T11:55:56Z")

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I am getting infrequent 404 errors even though the backend servers are running. I even tried to set only one backend server, and the result is the same.

backend keycloak\_servers  
timeout connect 10s  
timeout server 120s  
mode http  
balance roundrobin  
#cookie SERVER insert indirect nocache  
#http-request set-header X-Forwarded-Proto https if { ssl\_fc }  
http-request set-header X-Forwarded-Host %[req.hdr(Host)]

```
http-check expect status 200  
	http-check send meth GET uri /Keycloak
    server micro1 myip1:8443 ssl verify none check inter 5s fall 3 rise 2
    server micro2 myip2:8443 ssl verify none check inter 5s fall 3 rise 2

```

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**Author:** ![lukastribus](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@lukastribus](https://discourse.haproxy.org/u/lukastribus)\
**Post date:** [February 22, 2025, 11:59am UTC](https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628/2 "2025-02-22T11:59:28Z")

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Haproxy never generates 404 errors. Common errors that haproxy emits are in the 5xx range, when backend servers cannot be reached, etc, but not 404 (unless very specific configurations are applied like a specific error files with a 404 header).

Enable http logging and check what actually happens, so you can confirm whether this 404 comes from micro1 or micro2.

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<div class="post-metadata">

**Author:** ![Tom2](https://avatars.discourse-cdn.com/v4/letter/t/97f17d/32.png) [@Tom2](https://discourse.haproxy.org/u/Tom2)\
**Post date:** [February 22, 2025, 12:22pm UTC](https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628/3 "2025-02-22T12:22:56Z")

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Here some log entries, one 404 out of 4 calls. I also tested the Keycloak call from Postman, and some calls were receiving 404 even though the calls should be identical

Call from app  
2025-02-22T12:28:00.091358+00:00 myproxyserver haproxy[378612]: myip:39630 [22/Feb/2025:12:28:00.089] cms-main~ appservers/app2 0/0/1/1/2 404 400 - - --NI 2/2/1/1/0 0/0 “POST /realms/Keycloak/protocol/openid-connect/token HTTP/1.1”

Some others  
2025-02-21T23:11:07.875811+00:00 myproxyserver haproxy[429750]: ip1:45952 [21/Feb/2025:23:11:07.866] cms-main~ keycloak\_servers/micro2 0/0/4/5/9 200 3201 - - ---- 2/2/0/0/0 0/0 “GET /realms/Keycloak/protocol/openid-connect/certs HTTP/1.1”  
2025-02-21T23:21:11.800887+00:00 myproxyserver haproxy[434104]: ip2:56934 \*\*1/Feb/2025:23:21:11.778] cms-main~ keycloak\_servers/micro2 0/0/5/16/21 404 2307 - - ---- 1/1/0/0/0 0/0 “GET [https://myproxyserver.corp.x.com/realms](https://myproxyserver.corp.x.com/realms) HTTP/2.0”  
2025-02-21T23:21:21.929074+00:00 myproxyserver haproxy[434104]: ip2:56934 [21/Feb/2025:23:21:21.910] cms-main~ keycloak\_servers/micro2 0/0/0/17/17 200 903 - - ---- 1/1/0/0/0 0/0 “GET [https://myproxyserver.corp.x.com/realms/Keycloak](https://myproxyserver.corp.x.com/realms/Keycloak) HTTP/2.0”  
2025-02-21T23:21:42.683563+00:00 myproxyserver haproxy[434104]: ip2:56934 [21/Feb/2025:23:21:42.631] cms-main~ keycloak\_servers/micro2 0/0/0/51/51 200 3760 - - ----

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<div class="post-metadata">

**Author:** ![lukastribus](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@lukastribus](https://discourse.haproxy.org/u/lukastribus)\
**Post date:** [February 22, 2025, 1:06pm UTC](https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628/4 "2025-02-22T13:06:49Z")

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All of those log lines clearly indicate that it is the backend server that is returning the 404 response.

`appservers/app2` as well as `keycloak_servers/micro2`.

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<div class="post-metadata">

**Author:** ![Tom2](https://avatars.discourse-cdn.com/v4/letter/t/97f17d/32.png) [@Tom2](https://discourse.haproxy.org/u/Tom2)\
**Post date:** [February 24, 2025, 12:48pm UTC](https://discourse.haproxy.org/t/haproxy-returns-404-sometimes-even-though-the-backend-server-is-running/11628/5 "2025-02-24T12:48:12Z")

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I found the issue. I had two haproxy instances running hence one of them was serving the requests sometimes. I terminated the incorrect one with appservers/app2 and now haproxy is working as expected